• Energy Research

In the present study, simulation of a divided wall column (DWC) was carried out to study the product quality and energy efficiency as a function of reflux rate, liquid spilt and vapour split for the separation of C4-C6 normal paraffin ternary mixture. Rigorous simulation of the DWC was carried out using Multifrac model of ASPEN Plus software. Box-Behnken design (BBD) was used for the optimization of parameters and to evaluate the effects and interaction of the process parameters such as reflux rate (r), liquid split (l) and vapour split (v). It was found that the number of simulation runs reduced significantly for the optimization of DWC by BBD. Optimization by BBD under response surface methodology (RSM) vividly underscores interactions between variables and their effects. The predictions agree well with the results of the rigorous simulation.

Study aims to experimentally investigate the physical significance of continuously evolved kinetic parameters i.e.lnAapp and Eapp including the importance of parameters, i.e., m and c, in the kinetic compensation effect (KCE) lnAapp = mEapp + c during steam gasification of char. To gain further insights into the char gasification mechanism in the steam atmosphere, an understanding of KCE is desirable. Two low-rank coals, viz., Loy Yang brown coal and Collie sub-bituminous coal samples of particle sizes 106150 µm and 180212 µm, are selected for fluidized bed gasification. The high-sensitive, quadrupole mass spectrometer (QMS) is used to measure the product gas composition for determining the instantaneous rate of char-H₂O reactions. Results suggest that the difference in Eapp with the change in coal sample at fixed conversion level, signifies the relative condensation of residual char, whereas the respective differences in lnAapp reflects the difference in the relative proportion of active sites consumed during char gasification under the reaction controlled by the chemical reactivity of char. However, the continuous variation in Eapp with conversion in the event of char gasification of any coal sample, displays the change in the rate of surface reaction following surface desorption with conversion and the variation of lnAapp potentially presents the change in the rate of adsorption of gasifying agents with conversion. In the subsequent KCE, the slope ‘m’ shows the reactiveness of char by displaying the impact of change in the rate of surface reaction with the desorption on the rate of surface adsorption during char gasification. The degree of deviation in char reactivity due to the evolution of KCE from a foreseeable condition of having non-KCE is indicated by intercept ‘c’.

Abstract Computational modeling using the high-viscosity laminar flow approach was applied to study the effect of slab crossing time on slab heating and scale growth. Simulation of an existing industrial walking beam reheating furnace with four zones, outer refractory body, skid, slab, and fluid zone is considered. The fuel used was a mixture of coke oven and blast furnace gas. Preheated air is supplied co-axially with the fuel mixture. The combustion simulation is performed using the constrained equilibrium mixture fraction model. From the results, it has been observed that with an increase in slab residence time, the slab temperature and scale growth increase across the slab. For the system considered, with a fuel mass flowrate of 70,000 kg/h, 150–180 min of slab crossing time is appropriate to obtain desired slab temperature at the discharge end. The overall equivalence ratio is taken as Φ = 1 (fuel/air ratio is the same as stoichiometric ratio). The maximum slab scale thickness is evaluated as 2.4 mm at the discharged end for 180 min of slab crossing time.

AbstractGlobal urbanization and industrialization are energy‐intensive processes. Among different energy resources, fossil fuels meet more than 80 % of the energy demand. The factors such as the depletion of fossil fuel reserves, the unstable price of fossil fuels, and the emission of greenhouse gases (GHGs) due to the burning of fuels draw researchers’ attention towards the development of renewable and sustainable fuels. In this context, biomass may fill the gap between energy demand and petroleum availability in the foreseeable future. Moreover, half of this bioenergy comes from conventional uses of biomass, primarily in cooking and heating, as well as within small‐scale industries (such as charcoal kilns and brick kilns). The Biomass‐to‐Liquid (BTL) technology using Fischer‐Tropsch synthesis (FTS) and the Methanol process offers advantages over the traditional use of biomass. The FT/Methanol process is a propitious route to produce carbon‐neutral, ultra‐clean fuels that generate regulated emissions, including NOx, SOx, and PM. In this article, we have reviewed the processes of biomass gasification, syngas cleaning and conditioning, FTS and methanol synthesis.

AbstractThe Fischer–Tropsch (FT) process is an alternative route to produce petroleum crude equivalent, as this process converts carbonaceous feedstock‐derived (e.g. coal, biomass, natural gas) syngas to synthetic liquid fuels and chemicals. The technology also is known as gas‐to‐liquid (GTL), coal‐to‐liquid (CTL) and biomass‐to‐liquid (BTL) depending on the source of the syngas. Global demand for clean transportation fuels, volatile oil prices, unstable market scenarios and dwindling reserves of petroleum crude are the major drivers for fostering the FT process. FT‐derived synthetic liquid fuel has enormous potential to replace petroleum crude‐based transportation fuels. There is a possibility that individual countries can produce significant shares of their fuel using CTL, GTL and BTL technologies which help during shortages/peak oil circumstances. The present article summarizes the development of conversion of the different carbonaceous feedstock to liquid fuel including syngas generation, as well as catalytic conversion to liquid fuel via the FT route. © 2020 Society of Chemical Industry